Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability of extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as the travel from an outer suction port toward a center discharge port. The means for causing the orbiting of one of the scroll members is in many cases an electrical motor. The electric motor operates to drive the one scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
Scroll compressors depend upon a number of seals to be created to define the moving or successive chambers. One type of seal which must be created are the seals between opposed flank surfaces of the wraps. These flank seals are created adjacent to the outer suction port and travel radially inward along the flank surface due to the orbiting movement of one scroll with respect to the other scroll. Additionally sealing is required between the end plate of one scroll member and the tip of the wrap of the other scroll member. Because scroll compressors depend upon the seals between flank surfaces of the wraps and the seals between the end plates and opposing wrap tips, suction and discharge valves are generally not required.
While the prior art scroll machines are designed to run trouble free for the life of the scroll machine, it is still necessary to monitor the operation of the compressor and discontinue its operation when specific criteria have been exceeded. Typical operational characteristics which are monitored include the discharge temperature of the compressed refrigerant, the temperature of the motor windings, three-phase reverse rotational protection, three-phase missing phasesingle phase protection and an anti-short cycle. The monitoring of these characteristics and the methods and devices for monitoring these characteristics have been the subject of numerous patents.
Recently, it has been found that by monitoring the vibrational characteristics of the scroll machine, it is possible to predict problems with a scroll machine before these problems result in a failure to the entire system. For instance, in a refrigeration or air conditioning system which incorporates numerous scroll machines, the abnormal vibration of one of the scroll machines can result in a fracture of the refrigeration tube associated with that individual scroll machine. The fracture of this tube will result in a total loss of the system refrigerant, possible damage to property, expensive repairs and in some cases could be hazardous. Assignee's U.S. Pat. No. 5,975,854, the disclosure of which is incorporated herein by reference disclosed a device which is capable of independently monitoring the vibrational characteristics of an individual scroll machine.
Accordingly, what is needed is a system which is capable of communicating with and monitoring the operational characteristics of a compressor and/or a group of compressors. The system should have the ability to monitor all aspects of the operational characteristics of each of the compressor as well as having the ability to communicate with a central monitoring system to identify current or possible problems associated with the individual compressor. The central monitoring system can be a centralized rack gateway which communicates with each individual compressor, a rack/system control that acts as a gateway to communicate with each individual compressor or an Internet web server that communicates with a gateway associated with each compressor.
The present invention provides the art with an advanced compressor control and protection system. The advanced compressor control and protection system incorporates internally integrated sensing, protection and control functions not provided by the prior art motor protection modules in use today. The control and protection system of the present invention integrates these functions with the compressor for improved overall system cost, reliability and value and thus provides improved compressor protection, simpler system wiring, diagnostics and communications. The advanced compressor control and protection system of the present invention provides a common hardware platform for a broad range of compressor modules. The system of the present invention provides a reduction in cost due to common electronics platform for all sensing and control functions, higher reliability due to improved protection because of common logic incorporating a multiplicity of sensor and status information as well as reduction in cost and improved reliability due to reduction in field wiring of individual stand-alone protection systems.
The present invention utilizes a low-cost communications enabling approach using intermediate communications protocol to facilitate use of adapters and gateways for virtually any communications network with minimal cost burden on non-network applications. Multiple sensors are adapted for use internally within the compressor which provide signals which are analogous to the actual physical quantities being measured. Examples are discharge temperature, motor winding temperatures, gas pressure (suction, discharge) and differential pressures, liquid level, liquid refrigerant, relative percentage of liquid refrigerant versus oil and others.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.